"I'm anticipating they will be charged with failing to pay taxes and filing a false tax return," said Douglas de Vlaming, the Clearwater attorney representing Rober and his wife, Averill. "I think it's a very sad situation for which they are taking full responsibility."

De Vlaming said the U.S. Attorney's Office is investigating his clients. Officials with the U.S. Attorney's Office and IRS declined to comment.

It remains unclear how much income the couple failed to report, but de Vlaming said simply paying back the IRS would not be enough to avoid criminal charges.

"It doesn't work that way," he said. "The message is make sure you disclose all your income."

Rober, 52, announced his resignation Wednesday evening in City Hall, reading a prepared statement with his wife by his side and supporters in the room. He told the Times afterward that the IRS audit stemmed from a civil lawsuit filed in 2009.

The Robers are former owners of Gator Water and Wastewater Management Inc., a Pasco utility contractor. After Rober first took office in 2007, the couple sold their business to a Hudson utility operator known as Florida Utility Group Holdings Inc., with a promise that their company was free of all debts.

But the lawsuit claims a closer review by the new owners revealed an orchestrated operation by Rober during his years as Gator Water vice president to funnel about half a million dollars of company money into a personal fund he hid from accountants, the utility and the IRS.

That lawsuit is still pending, but has been put on hold for more than a year, according to Florida Utility Group's attorney John Colton. Now the lawsuit may be put off longer as they await the outcome of Rober's possible federal legal troubles, according to Colton.

Colton scoffed at Rober's explanation that his tax problems stemmed from the lawsuit.

"It stems from him not paying his taxes," Colton said. "I can say that my client was terribly surprised at what he found when he bought this company."

This is not the first time Rober has been investigated over financial dealings.

In 1994, he was arrested and charged with two counts of grand theft and two counts of perjury in Hernando County, where he helped his father run a business called Rober Construction. Authorities at the time said Rober signed paperwork that falsely stated that subcontractors had been paid for work on an office building.

Rober said his father's death in the summer of 1994 sent the company into financial disarray, leading to bankruptcy for the business.

On Thursday he said he fully cooperated with authorities in Hernando, and that the 1994 arrest was the only mechanism authorities had to begin the process of paying the subcontractors, which he said he welcomed.

Rober said he entered into a court diversion program in which he could make payments to the subcontractors, which eventually amounted to around $38,000. He said he does not remember the final adjudication in the case, but he had the matter expunged around 2007 or 2008.

"It was clear I never took any money from anyone," he said.

Rober said he has garnered support from the community since announcing his resignation, but left it up to others to decide what the public's perception of him may be. In the meantime, he said, he and his wife continue to work at their jobs: He is a salesman for BETER Mix concrete company, and his wife is a personal trainer.

"Maybe this is another hurdle we have to get past. Sometimes those hurdles will try you," Rober said. "But I want to make it clear that we are taking full responsibility for this."

Times staff writer Lee Logan and researcher Natalie Watson contributed to this report.

What's next?

• Richard Rober's resignation as mayor goes into effect Saturday.

• Vice Mayor Bill Colombo will take the reins as acting mayor until a replacement is selected.

• Pasco Supervisor of Elections Brian Corley plans to recommend Port Richey hold a mayoral election in conjunction with the Aug. 14 primary, which would cost less than holding a special election. But it's the city's call. "They're all shell-shocked over there," Corley told the Times. "They said, 'We need a couple days to digest this.'"